Challenges in Modelling and Optimization of Stability Constants in the Study of Metal Complexes with Monoprotonated Ligands - Part Ii - A Glass-Electrode Potentiometric and Polarographic Study of the Copper(Ii)/2-Hydroxy-3-[(2-Hydroxy-1,1-Dimethylethyl)Aminolpropane-1-Sulfonic Acid (Ampso)/Hydroxy System